“China Black”: Studio Potter Photos

Note: If you click either of the small images, you’ll get one that is 800 pixels across. I’ve also provided links to larger versions for those who are interested.

Figure 1:

An early attempt at copying the Black Ding glaze, starting from the analysis in Chinese Glazes. This bowl was fired to cone 10.5, in reduction, in Edwin Gould’s gas kiln, in Columbia, Maryland. Despite the relatively high firing temperature, it is teadusty and underfired. Nigel Wood’s analysis has 16.7% Alumina, which seems relatively high for a cone 9 glaze, and this bowl helped me decide that I should decrease the amount of clay in my formula.

1768 x 1704 pixels



Figure 2:

Vase, Helios porcelain (from Highwater); “China Black” glaze, fired to cone 9 in an electric kiln, with a hold at peak temperature. The piece is just under 4" tall.

There is a slight difference between this glaze and the recipe in the article -- I ran out of high-purity RIO while mixing this batch, and used 84% pure RIO to make up the balance. Either way, the glaze is quite well behaved, and I routinely apply it to within a millimeter of the foot. There is, of course, no way to know in advance how it will behave on your clay in your kiln, so I must repeat the Glaze Tweak creed: test, test, test!

1680 x 2256 pixels



Let’s Run Some Numbers

Here is the recipe, with Seger and Weight Percentage breakdowns:


Joss Research “China Black” v1.0 (Cone 9 oxidation)

G-200 Feldspar        38
Sapphire Kaolin       10
Silica                25
Whiting               15
Magnesium Carbonate    3
Red Iron Oxide (98%)   9

==========================

Seger Numbers:

K2O          0.163
Na2O         0.082
CaO          0.626
MgO          0.128

Al2O3        0.432

SiO2         3.628

Fe2O3        0.227
TiO2         0.007

(SiO2:Al2O3 ratio 8.4)

=========================

Weight Percentages:

SiO2         60.62
Al2O3        12.25
K2O           4.27
Na2O          1.41
CaO           9.77
MgO           1.44
Fe2O3        10.08
TiO2          0.16



Continuing Work

(08 December, 2004)

I am working on a slightly more traditional version of this glaze, using Redart Clay as the primary ingredient. If this pans out, I’ll put at least one recipe and a photo here.



Note: The photos were taken on September 25th, 2004, with a Canon G3 camera, in daylight. The camera records 2272x1704 pixels, the common 4-megapixel format. I chose the G3 by comparing digital camera reviews and discovering that it had slightly better resolution than almost all of the other cameras in its price/performance range, and that its specifications were, in general, quite good. It also offered focus bracketing, which was not available on any other ordinary digital camera at the time, and it has a fully manual mode. The digital camera world, however, is constantly changing, and I don’t know the current state of the art. (I did recently notice a very good review of the Canon G6, though.)



“Red Tenmoku”, another glaze project

To the Studio Potter Website



This work is supported by
The Joss Research Institute
19 Main St.
Laurel  MD  20707-4303   USA




Contact Information:

My email address is a@b.com, where a is jon and b=joss.

My phone number is +1 240 604 4495.

Last modified: Fri Dec 22 19:52:49 EST 2006